The bulk propagation speed of GeV-energy cosmic rays is limited by frequent scattering off hydromagnetic waves. Most galaxy evolution simulations that account for this confinement assume the gas is fully ionized and cosmic rays are well coupled to Alfvn waves; however, multiphase density inhomogeneities, frequently underresolved in galaxy evolution simulations, induce cosmic-ray collisions and ionization-dependent transport driven by cosmic-ray decoupling and elevated streaming speeds in partially neutral gas. How do cosmic rays navigate and influence such a medium, and can we constrain this transport with observations? In this paper, we simulate cosmic-ray fronts impinging upon idealized, partially neutral clouds and lognormally distributed clumps, with and without ionization-dependent transport. With these high-resolution simulations, we identify cloud interfaces as crucial regions where cosmic-ray fronts can develop a stairstep pressure gradient sufficient to collisionlessly generate waves, overcome ion–neutral damping, and exert a force on the cloud. We find that the acceleration of cold clouds is hindered by only a factor of a few when ionization-dependent transport is included, with additional dependencies on magnetic field strength and cloud dimensionality. We also probe how cosmic rays sample the background gas and quantify collisional losses. Hadronic gamma-ray emission maps are qualitatively different when ionization-dependent transport is included, but the overall luminosity varies by only a small factor, as the short cosmic-ray residence times in cold clouds are offset by the higher densities that cosmic rays sample.

GeV 能量宇宙射线的整体传播速度受到水磁波频繁散射的限制。大多数解释这种限制的星系演化模拟都假设气体完全电离并且宇宙射线与阿尔芬波很好地耦合；然而，在星系演化模拟中经常未得到充分解决的多相密度不均匀性会引起宇宙射线碰撞和由宇宙射线解耦和部分中性气体中流动速度提高驱动的电离相关传输。宇宙射线如何导航和影响这种介质，我们能否通过观测来限制这种传输？在本文中，我们模拟宇宙射线锋撞击理想化的、部分中性的云和对数正态分布的团块，有或没有依赖于电离的传输。通过这些高分辨率的模拟，我们将云界面确定为关键区域，在这些区域中，宇宙射线锋可以形成阶梯压力梯度，足以无碰撞地产生波，克服离子中性阻尼，并对云施加力。我们发现，当包括依赖于电离的传输时，冷云的加速仅受到几个因素的阻碍，另外还依赖于磁场强度和云维数。我们还探讨了宇宙射线如何对背景气体进行采样并量化碰撞损失。当包含依赖于电离的传输时，强子伽马射线发射图在性质上有所不同，但整体光度仅变化很小的因素，因为宇宙射线在冷云中的短暂停留时间被宇宙射线采样的更高密度所抵消。